This invention relates to imaging and inspection devices and particularly to tubing weld seam inspection devices used in combination with conventional tube forming machines.
A tube forming machine is a device which takes strip stock from a roll and, through a series of operations, converts it into a welded tube. The first step of the process is edge conditioning where rust and uneven edges are removed. The strip then passes between a series of rollers mounted on shafts where a curve is formed in the strip. At every pass after that, the radii gets smaller so that the strip takes the form of a cylinder in preparation for welding.
In a typical manufacturing operation, the tubing thus formed is moving along its longitudinal axis at a high rate of speed and, therefore, timely inspection is critical. Without such timely inspection, tremendous amounts of material would be wasted due to the improper seam alignment and the resulting low quality seam weld.
Ideally when tubing is formed from strip stock on conventional tube forming machines, both edges of the strip are joined in the weld box at the same height. Previous to the present invention, the most common method for inspection for edge alignment was for the operator to hold his gloved hand on the weld seam. This was not a desirable condition for safety and accuracy reasons. Off-line, the inspector could cut samples and inspect them under a microscope, but that required too much time to detect and take corrective action. What was needed was an on-line, non-contact, real-time monitoring system to measure edge alignment. However, as a result of the edge conditioning, tube forming, and welding processes, the environment becomes very dirty, and it is in this dirty environment that the inspection is expected to take place.
The present invention provides a low cost, simple and easy to implement vision system to detect edge misalignment, and is designed to operate in a dirty environment. In accordance with the present invention, a live image is displayed on a monitor.
Imaging and inspection systems are known in the prior art. See, for example, Shiozumi et al., U.S. Pat. No. 4,734,766; Tsikos, U.S. Pat. No. 4,979,815; Heesemann, U.S. Pat. No. 4,839,994; Rottenkolber et al., U.S. Pat. No. 4,111,557; White, U.S. Pat. No. 4,498,778; Wang et al., U.S. Pat. No. 4,812,614; Clocksin et al., U.S. Pat. No. 4,616,121; Masaki et al., U.S. Pat. No. 4,492,847; Nayar et al., U.S. Pat. No. 4,988,202; Kremers et al., U.S. Pat. No. 4,596,919; Case, Jr. et al., U.S. Pat. No. 4,542,279; Povlick et al., U.S. Pat. No. 4,590,356; Fryer New Product Bulletin, 1989, Subject: Light Sectioning; and Oldelft, The Robot's Eye, undated.
The present invention constitutes a significant improvement over the prior art because it is relatively low cost, easy to install, and effective for the purpose intended, i.e., readily to show that the seam weld produced by a conventional tube forming machine is out of specification. For instance, the prior art shows lasers used to monitor seams in manufacturing processes, but the prior art systems involve complicated laser scanning techniques and monitoring techniques for laser scanning, or complicated algorithms to analyze the data provided by the laser image.
According to the present invention an apparatus is provided for visualizing a longitudinal seam weld on a moving tube in a conventional tube forming environment, wherein the apparatus comprises means for projecting a steady plane of light on the tube seam weld as the tube moves longitudinally past the projecting means, means for imaging a reflection of the projected light from the tube seam weld, and means for displaying the reflection image. It also provides an apparatus for visualizing a seam weld on a moving tube, wherein the apparatus comprises a laser light source, lens means for forming the laser light into a steady plane of light, a plurality of mirrors to direct the plane of light to intersect the tube seam weld and to direct the reflection of the intersection to a camera, and a monitor to display the reflection imaged by the camera.
The present invention also provides an apparatus for visualizing a seam weld on a tube moving longitudinally in the direction of its axis, wherein the apparatus comprises a container formed to include an interior region and an aperture facing the moving tube and its seam weld, the container being positioned in spaced-apart relation to the tube seam weld. It further comprises light means for providing a planar light, the light means being mounted in the interior region, means for directing the planar light out of the interior region of the container through the aperture to intersect the tube seam weld, wherein the directing means are mounted in the interior region. It further comprises means for imaging the light pattern on the tube seam weld, the imaging means being mounted in the interior region, means for displaying the imaged points of intersection connected to the imaging means, the displaying means being positioned outside the container, source means for supplying electrical power to the light source and the imaging means, the power source means being mounted in the interior region, and transparent means for covering the aperture to keep workplace contaminants out of the interior region.
The present invention also provides an apparatus for optically determining departures in shape of a workpiece, where the apparatus comprises a container formed to include an interior region and an aperture, the container being positioned in spaced-apart relation to the workpiece, a planar light source mounted in the interior region, and a camera mounted in the interior region. It further comprises a plurality of mirrors arranged in the interior region to direct the planar light through the aperture to intersect the workpiece and to direct the reflection of the light pattern which passes through the aperture toward the camera, a power supply mounted in the interior region to provide electrical power to the apparatus, and a transparent aperture cover attached to the container in an aperture closing position to keep workplace contaminants out of the interior region.
The present invention further provides an edge alignment measuring system for inspecting alignment of a pair of edges of a strip that abut one another at a seam weld to form a tube, wherein the system comprises means for projecting a steady plane of coherent light across the seam of the tube to produce a first light pattern on one of the edges and a second light pattern on the other edge. It further provides means for displaying the first and second light patterns side-by-side to indicate a discontinuity between the first and second light patterns so that misalignment of the edges relative to one another is detected.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.